The present invention relates generally to position determination, and more particularly determining the position, location or coordinates of objects, or points in an image with respect to a coordinate system other than the local coordinate system of the image itself.
Determining the position of various objects in an image is useful for understanding the distance between objects or possibly the absolute distance between an object and another object that may not be in the image. Positions of objects in an image are usually determined by taking a photograph of an area. In the photograph there is usually a reference object whose position is known. The position of the other objects in the image is determined by computing the distance away from the reference object with the known position. The reference object with the known position enables the other objects to have known positions within the coordinate system of the photograph as well as a coordinate system that may be outside of the photograph.
Another way of determining the approximate positions of objects is simply by GPS image tagging. A GPS enabled camera may be utilized to take photographs. Each photograph may be tagged with the GPS information of the location of the camera when the photograph is taken. The GPS information can be associated with the captured image via a time stamp of both the GPS information and the image or the GPS image can simply be embedded in the digital data of the photograph. Unfortunately. GPS tagging only records the position of the camera when the photograph was captured. The GPS positions of objects in the photograph are still unknown.
Another method of determining positions of objects is through surveying. Surveyors use optical instruments to locate and/or triangulate positions on the ground. For example, a surveyor may be required to survey the boundaries of a property. Usually, the surveyor will find the nearest monument that has a known position. In this example, the monument may be several blocks from the property that may be required to survey. Once a monument is located, the surveyor uses optics and a human eye to physically measure distances from the monument. Unfortunately, surveying is prone to errors such as optical errors and human eye errors. Also, the surveying method only determines the position of a single point at a time with a great deal of effort.
Unfortunately, many of the systems and methods described above have problems. The position of an object may still be required even when there are no positions of reference objects available. Multiple points may need to be determined simultaneously. Accuracy, greater than the errors inherent in the human eye and optics may be required.